Re: speedup of modifying return values

[Matt Wette]

On 08/29/2018 03:58 AM, Stefan Israelsson Tampe wrote:
> Hi all, I'm trying to make a python clone in guile. Currently the code 
> is slow and one of  the reasons is the following,
>
> in my pythoon
>
> return 1,2
>
> returns a (values 1 2) in order to get python and scheme to 
> interoperate. but for python if you use
>
> x = 1,2
>
> then x is the tupple '(1 2) and in guile it is 1. So therefore we wrap 
> the result for
>
> x=f(10)
>
> as
> (set! x (call-with-values (lambda () (f x)) (case-lambda ((x) x) (x x))))
>
> This can be compiled to efficient bytecode but is not done so in 
> guile. In stead a closure is created at each assignment site and 
> creating ineficient code.
>
> Any ideas how to improve this (I don't want "return a,b" to mean (list 
> a b) which is a quick solution
> if we want to just stay in python and not interoperate with scheme at 
> all on this level.
>
> Regards
> Stefan

So I'm working on extension languages in Guile.  I assume you are always 
returning tree-il
values from Python functions.  (Unless from functions returning tuples, but how 
do you
guarantee that?)  You could add a property to your functions and then compile 
to CPS and
do the optimization yourself.  Then convert to bytecode.  But that seems tough.

I assume the use case is being able to call Python code from Guile, so one 
would always call
from Scheme using call-with-values?

I am using call-with-values in nx-matlab when the function is declared with 
multiple values.

Also, I wonder if we should be "marking" functions with a property to indicate 
what the
source language is.  The property could be 'language.  (If no language assume 
'scheme.)


Matt